Description of Business and Organization Description of Business and Organization Narrative (Details)	0 Months Ended	6 Months Ended
	Oct. 06, 2013 entity	Jun. 30, 2014 entity sqft	Jun. 30, 2014 Office Building [Member] sqft office_and_property	Jun. 30, 2014 Office Building [Member] Manhattan [Member] sqft office_and_property	Jun. 30, 2014 Office Building [Member] Fairfield County, Connecticut and Westchester County, New York [Member] office_and_property sqft	Jun. 30, 2014 Development Parcel [Member] parcel	Jun. 30, 2014 Retail Site [Member] Manhattan and Westport, Connecticut [Member] sqft	Jun. 30, 2014 Retail Site [Member] Manhattan [Member] sqft office_and_property	Jun. 30, 2014 Retail Site [Member] Westport, Connecticut [Member] office_and_property	Jun. 30, 2014 Other Property [Member] Stamford, Connecticut [Member] sqft	Jul. 15, 2014 Subsequent Event [Member] office_and_property	Jul. 15, 2014 Subsequent Event [Member] Office Building [Member] sqft	Jul. 15, 2014 Subsequent Event [Member] Retail Site [Member] sqft
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property		8,400,000	7,800,000	5,900,000	1,800,000		204,175	415,339		380,000		1,500,000	112,270
Number of properties			12	7	5	1		4	2		2
OP units owned by the Company, percent		38.90%
Number of entities to be treated as taxable REIT subsidiary		2
Number of entities acquired	4	4